"""Tenant-scoped helpers for checking and deducting LLM provider quota.

System-hosted quota accounting is currently defined only for LLM models. Keep
the public helpers LLM-specific so callers do not carry unused model-type
plumbing, and fail loudly if the deprecated ``ModelInstance`` wrappers are used
with a non-LLM model.
"""

import warnings

from sqlalchemy import select
from sqlalchemy.orm import sessionmaker

from configs import dify_config
from core.entities.model_entities import ModelStatus
from core.entities.provider_entities import ProviderQuotaType, QuotaUnit
from core.errors.error import QuotaExceededError
from core.model_manager import ModelInstance
from core.plugin.impl.model_runtime_factory import create_plugin_provider_manager
from extensions.ext_database import db
from graphon.model_runtime.entities.llm_entities import LLMUsage
from graphon.model_runtime.entities.model_entities import ModelType
from libs.datetime_utils import naive_utc_now
from models.provider import Provider, ProviderType
from models.provider_ids import ModelProviderID


def _get_provider_configuration(*, tenant_id: str, provider: str):
    """Resolve the tenant-bound provider configuration for quota decisions."""
    provider_manager = create_plugin_provider_manager(tenant_id=tenant_id)
    provider_configuration = provider_manager.get_configurations(tenant_id).get(provider)
    if provider_configuration is None:
        raise ValueError(f"Provider {provider} does not exist.")
    return provider_configuration


def ensure_llm_quota_available_for_model(*, tenant_id: str, provider: str, model: str) -> None:
    """Raise when a tenant-bound LLM model is already out of quota."""
    provider_configuration = _get_provider_configuration(tenant_id=tenant_id, provider=provider)
    if provider_configuration.using_provider_type != ProviderType.SYSTEM:
        return

    provider_model = provider_configuration.get_provider_model(
        model_type=ModelType.LLM,
        model=model,
    )
    if provider_model and provider_model.status == ModelStatus.QUOTA_EXCEEDED:
        raise QuotaExceededError(f"Model provider {provider} quota exceeded.")


def _resolve_llm_used_quota(*, system_configuration, model: str, usage: LLMUsage) -> int | None:
    """Compute the quota impact for an LLM invocation under the current quota mode."""
    quota_unit = None
    for quota_configuration in system_configuration.quota_configurations:
        if quota_configuration.quota_type == system_configuration.current_quota_type:
            quota_unit = quota_configuration.quota_unit

            if quota_configuration.quota_limit == -1:
                return None

            break

    used_quota = None
    if quota_unit:
        if quota_unit == QuotaUnit.TOKENS:
            used_quota = usage.total_tokens
        elif quota_unit == QuotaUnit.CREDITS:
            used_quota = dify_config.get_model_credits(model)
        else:
            used_quota = 1

    return used_quota


def _deduct_free_llm_quota(
    *,
    tenant_id: str,
    provider: str,
    quota_type: ProviderQuotaType,
    used_quota: int,
) -> None:
    """Deduct FREE provider quota, capping at the limit before reporting exhaustion."""
    quota_exceeded = False
    with sessionmaker(bind=db.engine).begin() as session:
        provider_record = session.scalar(
            select(Provider)
            .where(
                Provider.tenant_id == tenant_id,
                # TODO: Use provider name with prefix after the data migration.
                Provider.provider_name == ModelProviderID(provider).provider_name,
                Provider.provider_type == ProviderType.SYSTEM.value,
                Provider.quota_type == quota_type,
            )
            .with_for_update()
        )
        if (
            provider_record is None
            or provider_record.quota_limit is None
            or provider_record.quota_used is None
            or provider_record.quota_limit <= provider_record.quota_used
        ):
            quota_exceeded = True
        else:
            available_quota = provider_record.quota_limit - provider_record.quota_used
            deducted_quota = min(used_quota, available_quota)
            provider_record.quota_used += deducted_quota
            provider_record.last_used = naive_utc_now()
            quota_exceeded = deducted_quota < used_quota

    if quota_exceeded:
        raise QuotaExceededError(f"Model provider {provider} quota exceeded.")


def _deduct_used_llm_quota(*, tenant_id: str, provider: str, provider_configuration, used_quota: int | None) -> None:
    """Apply a resolved LLM quota charge against the current provider quota bucket."""
    if provider_configuration.using_provider_type != ProviderType.SYSTEM:
        return

    system_configuration = provider_configuration.system_configuration
    if used_quota is not None and system_configuration.current_quota_type is not None:
        match system_configuration.current_quota_type:
            case ProviderQuotaType.TRIAL:
                from services.credit_pool_service import CreditPoolService

                CreditPoolService.deduct_credits_capped(
                    tenant_id=tenant_id,
                    credits_required=used_quota,
                )
            case ProviderQuotaType.PAID:
                from services.credit_pool_service import CreditPoolService

                CreditPoolService.deduct_credits_capped(
                    tenant_id=tenant_id,
                    credits_required=used_quota,
                    pool_type="paid",
                )
            case ProviderQuotaType.FREE:
                _deduct_free_llm_quota(
                    tenant_id=tenant_id,
                    provider=provider,
                    quota_type=system_configuration.current_quota_type,
                    used_quota=used_quota,
                )
            case _:
                return


def deduct_llm_quota_for_model(*, tenant_id: str, provider: str, model: str, usage: LLMUsage) -> None:
    """Deduct tenant-bound quota for the resolved LLM model identity."""
    provider_configuration = _get_provider_configuration(tenant_id=tenant_id, provider=provider)
    used_quota = _resolve_llm_used_quota(
        system_configuration=provider_configuration.system_configuration,
        model=model,
        usage=usage,
    )
    _deduct_used_llm_quota(
        tenant_id=tenant_id,
        provider=provider,
        provider_configuration=provider_configuration,
        used_quota=used_quota,
    )


def _require_llm_model_instance(model_instance: ModelInstance) -> None:
    """Reject deprecated wrapper calls that pass a non-LLM model instance."""
    if model_instance.model_type_instance.model_type != ModelType.LLM:
        raise ValueError("LLM quota helpers only support LLM model instances.")


def ensure_llm_quota_available(*, model_instance: ModelInstance) -> None:
    """Deprecated compatibility wrapper for callers that still pass ModelInstance."""
    warnings.warn(
        "ensure_llm_quota_available(model_instance=...) is deprecated; "
        "use ensure_llm_quota_available_for_model(...) instead.",
        DeprecationWarning,
        stacklevel=2,
    )
    _require_llm_model_instance(model_instance)
    ensure_llm_quota_available_for_model(
        tenant_id=model_instance.provider_model_bundle.configuration.tenant_id,
        provider=model_instance.provider,
        model=model_instance.model_name,
    )


def deduct_llm_quota(*, tenant_id: str, model_instance: ModelInstance, usage: LLMUsage) -> None:
    """Deprecated compatibility wrapper for callers that still pass ModelInstance."""
    warnings.warn(
        "deduct_llm_quota(tenant_id=..., model_instance=..., usage=...) is deprecated; "
        "use deduct_llm_quota_for_model(...) instead.",
        DeprecationWarning,
        stacklevel=2,
    )
    _require_llm_model_instance(model_instance)
    deduct_llm_quota_for_model(
        tenant_id=tenant_id,
        provider=model_instance.provider,
        model=model_instance.model_name,
        usage=usage,
    )